Bearing cages for rolling-element bearings are generally comprised of two axially-spaced-apart side rings. A plurality of bridges that connect the side rings and are disposed one behind the other in a circumferential direction of the bearing cage. Each pair of bridges forms a pocket for accommodating and guiding a rolling element. A bearing cage holds the rolling elements spaced apart relative to each other, thereby preventing direct contact between neighboring rolling elements and thus reducing friction and heat generation in the bearing. The bearing cage also ensures a uniform distribution of the rolling elements around the entire circumference of the cage or rolling-element bearing and thus enables a uniform load distribution as well as a quiet and smooth running of the bearing.
Bearing cages are heavily stressed in operation through frictional, strain, and inertial forces. Therefore, they are generally constructed as one piece. Rolling-element bearing cages typically comprise pressed cages or solid cages. Pressed cages for rolling-element bearings are usually manufactured from sheet steel, in some cases also from sheet brass. Solid cages for rolling-element bearings can be manufactured for example from brass, steel, aluminum, polymers, or phenolic resin.
To develop more efficient internal combustion engines, it has been investigated to replace slide bearings, which have been used for crankshafts and piston or connecting rods, with rolling-element bearings, since significant friction reductions can be achieved in this way. However since crankshafts are in principle formed with a 90° offset, there are two possible ways to mount rolling-element bearings thereon. First, if the crankshaft is built from individual parts, the bearings can be mounted axially. Second, the bearings (and specifically the bearing rings and cage) can be split radially along a plane and mounted over the shaft journals. Since the construction of crankshafts from individual parts is generally very complicated and associated with high costs, under normal circumstances it is necessary to develop and deliver divided rolling-element bearings having cages that are also divided.
Both engines for use in racing and aircraft engines are known in the art in which rolling-element bearings have been used. From these cases, findings have been made that the forces occurring, in particular in piston rod bearing applications, necessitate a one-piece cage construction. This has resulted in the requirement to construct radially divided cages, which after assembly can be connected by “locks”, in order to fulfill their function as one-piece cages.
Divided or split roller-bearing cages have a through-slot at a cutting or parting line in the circumferential direction. The respective ends of the cage or side ring that border the cutting line are formed as bridges (circumferential bridges), which have projections and openings corresponding to one another, in order to fix or couple the cage ends to each other, for example using a snap-fit connection. Such split rolling-element bearing cages, in which a “lock” or a “latch” attached to the cage ends secures or fixes the cage ends, can be used in many ways, such as for example for the bearing of balance shafts or for the bearing of gears on shafts in motor vehicles having a manual transmission.
A variety of embodiments for a cage connection or a cage lock are known from the literature and from the prior art. These embodiments have up to now mainly been developed for applications in automobile transmissions and primarily to facilitate installation. In these applications, however, the forces occurring are relatively small, i.e. after assembly the cage locks are only lightly loaded. Also elastic cages, e.g. made from appropriate polymers, are primarily used with only one point of connection, which is bent open for installation and subsequently connected again by the lock. As a result, the requirements with respect to positioning and force support are substantially less than in newer applications in internal-combustion engines.